Long-term follow-up of Intacs in keratoconus

Criteria for patient selection and indication for intracorneal ring segments in keratoconus

BACKGROUND

Keratoconus is an ectatic, progressive corneal disorder characterized by alterations in the morphology of the corneal tissue that leads to limitation of visual function of the patient. Intracorneal ring segments (ICRS) are small synthetic devices that are implanted in the corneal stromal in order to regularize the morphology of the tissue therefore improving the visual function and the quality of life of the patients.

MAIN TEXT

The present narrative review summarizes the main scientific articles developed by the authors in relation to the clinical outcomes and long-term results of ICRS in the treatment of keratoconus. It was found that those patients that benefit the most from this surgical intervention are those that have the most severe form of keratoconus. Additionally, patients with good visual function, those with more than 0.9 in the decimal scale are at risk of losing visual acuity after ICRS implantation. In relation to long-term results, scientific investigations published by the authors demonstrate that ICRS is a stable procedure after long period of time in terms of vision, refraction, and topographic variables in those patients with stable keratoconus. However, in patients with keratoconus and signs of progression, ICRS may not have the capability of halting the progression of the disease. Using artificial intelligence to guide ICRS implantation provide better clinical outcomes and improvement in corneal higher-order aberrations in patients with keratoconus in comparison to those treated using the commercial nomogram of implantation.

CONCLUSIONS

ICRS is a safe surgical procedure in the treatment of keratoconus. Patients that benefit most from the surgery are those with a significant visual impairment. ICRS should not be considered in patients with good visual function because of the risk of losing lines of vision. Long-term follow-up demonstrate stability of the clinical outcomes in patients with stable keratoconus although ICRS may not have the ability of halting the progression of the disease. New technologies based artificial intelligence improved the indications and the clinical outcomes of keratoconus patients treated with ICRS.

Corneal Allogenic Intrastromal Ring Segments (CAIRS) for Corneal Ectasia: A Comprehensive Segmental Tomography Evaluation

PURPOSE

To evaluate the visual, refractive, and tomographic results of patients with corneal ectasia treated with corneal allogenic intrastromal ring segments (CAIRS) insertion without concomitant corneal cross-linking.

METHODS

Fifty-two eyes from 39 patients with stable corneal ectasia and unsatisfactory visual acuity with contact lenses were included. All patients underwent CAIRS insertion with no concomitant corneal procedure at the American University of Beirut Medical Center between September 2019 and July 2022. Visual, refractive, topographic, aberrometric, epithelial, stromal, and segment thickness data were measured relative to baseline at 1 week, 1 month, and at least 3 months postoperatively. Evaluations included slit-lamp examination, manifest refraction, uncorrected (UDVA) and corrected (CDVA) distance visual acuity, and tomography using anterior segment optical coherence tomography.

RESULTS

Mean follow-up time was 6.9 ± 5.2 months. UDVA and CDVA improved from 0.97 ± 0.47 and 0.56 ± 0.19 preoperatively to 0.52 ± 0.21 (P < .001) and 0.23 ± 0.19 (P < .001) 3 months postoperatively. Manifest refraction spherical equivalent and cylinder improved from -6.71 ± 6.51 and -4.02 ± 2.24 diopters (D) preoperatively to -3.78 ± 4.07 D (P < .001) and -2.35 ± 1.98 D (P < .001) 3 months postoperatively, respectively. Maximum anterior keratometry and vertical coma decreased from 58.09 ± 7.92 D and 1.56 ± 1.09 µm to 52.48 ± 6.69 D (P < .001) and 0.43 ± 0.77 µm, respectively (P < .001). Corneal epithelium thickened proximal to the allogenic segment by 7.25 µm (P < .001), whereas stromal elevation at the cone decreased from 38.61 ± 18.5 to 23.82 ± 13.4 µm, respectively (P < .001). No major complications were observed and only 1 eye lost one line of CDVA.

CONCLUSIONS

Treatment of corneal ectasia with CAIRS improved visual, refractive, topographic, and tomographic parameters. Epithelial thickening central to CAIRS, along with anterior stromal flattening is postulated to contribute to tomographic flattening and regularization. [J Refract Surg. 2023;39(11):767-776.].

Outcomes of two different treatment modalities in mild to moderate keratoconus

PURPOSE

To describe visual and refractive outcomes of intrastromal corneal ring segments (ICRS) and toric implantable collamer lenses (TICL) implantation in cases of mild and moderate keratoconus.

METHODS

A prospective descriptive interventional case series. 40 eyes were allocated into two groups. First group (20 eyes) was treated with corneal collagen crosslinking (CXL) 1 month after ICRS implantation and the second group was treated using TICL after 1 year of CXL.

RESULTS

Both groups showed statistically significant improvement in spherical equivalent, cylindrical refraction, uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA) over the follow-up period.

CONCLUSION

Both ICRS and TICL are effective in treatment of mid and moderate keratoconus with more predictable visual results with TICL.

Delayed Perforation of an Intrastromal Corneal Ring Segment into the Anterior Chamber: A Case Report and Review of the Literature

Intrastromal corneal ring segments (ICRSs) are an effective treatment for stabilizing and normalizing corneal shape in patients with keratoconus and other corneal ectasias. Intraoperative segment perforation through the corneal endothelium into the anterior chamber (AC) is an uncommon but known complication. However, perforation into the AC postoperatively is an exceedingly rare complication with only 3 reported cases in the literature. One case was due to Descemet membrane detachment and another due to ocular trauma. In the third case, the mechanism for perforation was unclear. We present the fourth case of delayed ICRS perforation due to silent migration through the endothelium into the AC. We also present all reported cases in the literature of intraoperative and postoperative perforation into the AC.

Combined Corneal Cross-Linking and Myoring Implantation in Advanced Keratoconus: Femtosecond Laser versus Manual Dissection

Background

Intrastromal corneal ring segments are widely adopted for keratoconus management. However, the complete ring (Myoring) was proposed to be superior in advanced cases. Myoring can be implanted either via femtoassisted or manual dissection techniques. A comparison between both techniques can delineate any differences in the outcomes.

Methods

This was a prospective interventional case series study. Sixty-four eyes with progressive advanced keratoconus were enrolled: 36 and 28 had femtoassisted or manual Myoring, respectively. Uncorrected visual acuity (UCVA), corrected distance visual acuity (CDVA), maximal keratometry (K _max), spherical equivalent (SE) and corneal thinnest location were measured in all eyes preoperatively and at one, six, and 12 months postoperatively. Epi-off corneal cross-linking (CXL) was performed eight weeks after Myoring implantation for all cases.

Results

Femtoassisted Myoring dissection significantly improved UCVA and CDVA from 0.1 ± 0.06 and 0.18 ± 0.1 preoperatively to 0.29 ± 0.08 and 0.43 ± 0.1 at 12 months. Also, manual technique similarly enhanced UCVA and CDVA from 0.11 ± 0.05 and 0.2 ± 0.1 preoperatively to 0.27 ± 0.2 and 0.4 ± 0.2 at 12 months. In terms of safety, while no cases of ring extrusion were encountered with the femtoassisted technique, six (21.4%) cases of extrusion were encountered in the manual group.

Conclusion

Femtoassisted or manual Myoring technique followed by CXL is an effective choice for advanced progressive keratoconus. Although it did not reach a statistical significance, the high extrusion rate with manual dissection is a red flag to be considered.

Comparison of Keratoconus Cone Location of Different Topo/tomographical Parameters

Purpose: To compare the corneal cone location on different maps and instruments, and their agreements, with elevation maps.Methods: In 90 left eyes with bilateral keratoconus, the apex of cone location was determined based on the maximum simulated keratometry (Kmax) location on the anterior sagittal curvature map by Pentacam HR, the maximum curvature on the mean curvature map by ATLAS 9000, most elevated point of the island of positive elevation relative to the best fit sphere on the front and back corneal elevation maps by Pentacam HR, and thinnest point on the thickness map by Pentacam HR and Orbscan, and the thinnest points on pachymetry and epithelial thickness maps by RTVue OCT.Results: There was a significant difference among the location on different maps along the x- and y-axes (p < .001). The lowest agreement with the cone apex on both front and back elevation maps was for the anterior sagittal curvature map and the highest agreement for the Pentacam thickness map. The majority of keratoconus cone apexes were displaced in the inferotemporal direction on the different maps except for the epithelial thickness maps.Conclusions: Despite the variability between different devices and methods; the thickness map on the Pentacam HR showed the highest correlation with the front and back elevation maps, while the RTVue epithelial thickness map showed the poorest correlation. Based on this study, epithelial thickness maps and anterior curvature maps should be utilized with caution to determine the location of the cone.

Effect of intracorneal ring segment implantation on high order aberrations comparing patients with eccentric versus central keratoconus

PURPOSE

To assess potential differences between central and eccentric cones in the aberrometric corneal profile and in visual and keratometric outcomes 6 months after intracorneal ring segment (ICRS) implantation for keratoconus.

METHODS

This study compared two groups consisting of 12 patients each, with central or eccentric keratoconus who were treated with femtosecond laser-assisted Keraring implantation. Uncorrected (UDVA) and corrected (CDVA) distance visual acuity, keratometric readings and higher order aberrations (HOAs) including high order aberrations root mean square (HOARMS), coma, spherical aberration and trefoil were measured preoperatively and 6 months after ICRS implantation.

RESULTS

Trefoil and spherical aberration were significantly reduced after ICRS implantation compared to preoperative values in eccentric keratoconus (Trefoil, p = 0.0049; Spherical aberration, p < 0.0001). In central keratoconus spherical aberration was reduced not significantly after ICRS implantation compared to preoperative values (p = 0.087). Coma showed a significant reduction in central (p = 0.0001) and in eccentric keratoconus (p = 0.0001). The reduction of spherical aberration in central keratoconus was significantly positively correlated to improvement in UDVA (Pearson's correlation coefficient, r = -0.66; p = 0.02). In eccentric keratoconus there was a significant positive correlation between reduction of trefoil and improvement in UDVA (Spearmans R, r = -0.69; p = 0.01).

CONCLUSION

Patients both with central and eccentric keratoconus benefit from ICRS implantation. Specifically, our data provide a slightly higher gain in visual performance for eccentric cones 6 month after ICRS implantation, which is accentuated by a greater reduction in spherical aberration and trefoil. Improvements in UDVA are positively correlated with reductions in HOAs.

Astigmatic Change as a Predictor of Intrastromal Corneal Ring Segment Late Extrusion

PURPOSE

To evaluate changes in keratoconic corneas implanted with intracorneal ring segments (ICRS) that have been explanted due to late extrusion of the segment after >2 years.

SETTING

Vissum Miranza, Alicante, Spain; OftalmoSalud, Lima, Peru; Minya University Hospital, Egypt.

METHODS

Retrospective, multicenter, series of cases of 23 keratoconic corneas that have been implanted for > 2 years and have been explanted due to natural extrusion of the segment. Clinical measures of visual, refractive, topographic, pachymetric and aberrometric data were analyzed. To perform exploratory factor analysis, the Kaiser-Meyer-Olkin (KMO) test was used to evaluate sampling adequacy. Factor analysis with VARIMAX rotation was used to determine the main factors of the inventory.

RESULTS

Mean time interval 5 years. Topographic findings were reversed nearly to the baseline level after segment explantation (p>0.05). Significant worsened in refractive cylinder was found pre-ICRS extrusion (p<0.05). KMO revealed a suitability of 0.528 in the preimplantation matrix (p<.001), 0.534 in the postimplantation matrix (p<.001), 0.549 in the preexplantation matrix (p=.009). Main factor obtained in the preimplantation moment included keratoconus grade, keratometric readings and visual acuities. After ICRS implantation, the most strength components were the refractive cylinder, CDVA and UDVA. Corneal aberrations were the main factors in the preexplantation analysis.

CONCLUSIONS

ICRS can be safely extracted, with a reversal of the corneal topographic data to the preoperative level. We showed a significant astigmatic change in patients implanted with ICRS before late extrusion of the segment, suggesting the role of this parameter as a prognostic factor of extrusion.

Five-year long-term outcomes of intrastromal corneal ring segment implantation using the manual technique for keratoconus management

PURPOSE

To evaluate the long-term effectiveness, safety, and stability of Ferrara-type intrastromal corneal ring segments (ICRS) by manual surgery implantation in patients with keratoconus.

SETTING

Ophthalmology Department, Hospital de Braga, Braga, Portugal.

DESIGN

Retrospective cohort study.

METHODS

This study included 124 eyes that had ICRS implantation using the manual technique with a follow-up of 5 years. Uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA), subjective refraction, keratometry, aberrometry, and pachymetry maps were evaluated preoperatively and at 6 months, 1 year, and 5 years postoperatively. A secondary analysis of all variables was performed comparing 2 subgroups of patients: a group younger than 30 years and a group of 30 years or older.

RESULTS

At 5 years, both mean UDVA and CDVA improved significantly (P < .0001) from a preoperative value of 0.91 ± 0.36 to 0.46 ± 0.32 logMAR and 0.40 ± 0.27 to 0.22 ± 0.20 logMAR, respectively. Spherical equivalent, refractive cylinder, and all topography values significantly decreased postoperatively (P < .0001). No regression was observed in any visual or topographic parameter during the entire follow-up. Regarding the subgroup analysis, both younger and older patients demonstrated similar and stable results from the preoperative to the 5-year visit, except for minimum pachymetry value change over time.

CONCLUSIONS

Ferrara-type ICRS implantation significantly improved visual acuity, refractive error, and topographic values; the improvement was stable throughout a 5-year follow-up period. This study confirms that ICRS implantation surgery for keratoconus is a stable procedure in a long-term follow-up, regardless of the preoperative patient's age.

CLEAR - Medical use of contact lenses

The medical use of contact lenses is a solution for many complex ocular conditions, including high refractive error, irregular astigmatism, primary and secondary corneal ectasia, disfiguring disease, and ocular surface disease. The development of highly oxygen permeable soft and rigid materials has extended the suitability of contact lenses for such applications. There is consistent evidence that bandage soft contact lenses, particularly silicone hydrogel lenses, improve epithelial healing and reduce pain in persistent epithelial defects, after trauma or surgery, and in corneal dystrophies. Drug delivery applications of contact lens hold promise for improving topical therapy. Modern scleral lens practice has achieved great success for both visual rehabilitation and therapeutic applications, including those requiring retention of a tear reservoir or protection from an adverse environment. This report offers a practical and relevant summary of the current evidence for the medical use of contact lenses for all eye care professionals including optometrists, ophthalmologists, opticians, and orthoptists. Topics covered include indications for use in both acute and chronic conditions, lens selection, patient selection, wear and care regimens, and recommended aftercare schedules. Prevention, presentation, and management of complications of medical use are reviewed.

Preliminary results of a new intrastromal corneal ring segment as a tissue saving procedure in photorefractive keratectomy to correct moderate to high myopia

AIM

To evaluate the clinical results after implantation of a new intrastromal corneal ring segment (ICRS) associated with photorefractive keratectomy (PRK) to correct high myopia (HM) patients with thin corneas.

METHODS

We evaluated 42 eyes of 23 HM patients that had ICRS implantation followed by PRK. The mean age of patients was 29.1±7.12y (range 18 to 40 years old). Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), keratometry, spherical equivalent, pachymetry, and aberrometry were compared using ANOVA with repeated measurements evaluated preoperatively and at last follow-up visit after the procedures. The refractive predictability and simulated/real corneal ablation were also assessed.

RESULTS

The mean follow-up time after PRK was 6.8±1.6mo. The mean preoperative UCVA improved from 20/800 preoperative to 20/100 after ICRS and 20/35 after PRK. The mean preoperative BCVA was 20/25 (range from 20/30 to 20/20) and remained unchanged after ICRS implantation. Following the PRK the mean BCVA was 20/25 (range from 20/30 to 20/20). The mean spherical equivalent decreased from -7.25±1.12 (range -5.00 to -9.00) preoperatively to -3.32±1.0 (range -2.00 to -5.00) postoperatively (P<0.001) after ICRS implantation and decreased from -2.44±1.51 preoperatively to 0.32±0.45 (range -0.625 to 0.875) postoperatively (P<0.001) after PRK. The change in BCVA and topographic astigmatism was statistically significant (P<0.0001).

CONCLUSION

ICRS in HM associated with PRK can be a tissue saving procedure and an alternative surgical option for correction of moderate to high myopia.

Biomicroscopic Findings and Management of Anterior Stromal Necrosis After Long-term Implantation of Intacs

PURPOSE

We sought to evaluate the visual, refractive, and biomicroscopic findings pre- and posttreatment of observed anterior stromal necrosis (ASN) after long-term Intacs intracorneal ring segment (ICRS) implantation.

DESIGN

Consecutive interventional case series.

METHODS

All consecutive patients implanted with Intacs ICRS at a single center by 1 of the authors between October 2006 and October 2011 with a minimum follow-up time of 5 years were included. All Intacs were implanted using the Prolate system console and instrumentation from Addition Technology Inc (Chicago, Illinois, USA). The slit lamp, refractive, and visual findings and the management of those patients are described in detail. The primary outcome measures included the size of the epithelial defect overlying the Intacs body, the intended implantation depth measured by high-magnification slit lamp photography, and the management of the cases described in detail. The percentage of eyes with ASN out of those that reached the 5-year follow-up is reported.

RESULTS

One hundred twenty-seven eyes (84 patients) were implanted with 215 ICRSs during the study period, and 77.16% (98/127) eyes had a follow-up of ≥5 years, out of which 9 eyes (7 patients) had ASN corresponding to at least 9.18% (95% confidence interval 4.29%-16.72%). The mean ± standard deviation time between implantation and ASN diagnosis was 10.5 ± 1.3 years.

CONCLUSION

After 5 years of implantation, INTACS-treated eyes could present with an ASN over the ICRS body. Longer-term follow-up of patients implanted with INTACS is important to monitor if this complication keeps occurring over time.

[Phacosurgery features in keratoconus]

The review summarizes the results of surgical treatment of cataracts in patients with keratoconus. The major challenges of phacosurgery in keratoconus are associated with intraocular lens (IOL) power calculation, choice of the most appropriate IOL model and additional interventions required to stabilize keratectasia and reduce corneal irregularity.

Visual, refractive and topographic outcomes of progressive thickness intrastromal corneal ring segments for keratoconic eyes

PURPOSE

To evaluate one-year visual, refractive, and topographic outcomes of 58 eyes of 53 keratoconus patients who underwent surgery with a progressive thickness intrastromal corneal ring segment (ICRS).

METHODS

This multi-center, retrospective, observational study evaluates the one-year effects of progressive thickness ICRS implanted in keratoconus patients meeting the inclusion criteria. One or two progressive ICRS were implanted in the selected eyes after creating an intrastromal tunnel with a femtosecond laser. Pre- and postoperative uncorrected distance visual acuity, best-corrected distance visual acuity, manifest refraction (both spherical equivalent and cylindrical refractions), corneal astigmatism, maximum keratometry, corneal thickness, and corneal topography measurements and indices were evaluated.

RESULTS

In this retrospective case series, 58 eyes of 53 keratoconus patients were included with a follow-up of 12 months. The mean age was 30.89 ± 11.90 years. There were improvements postoperatively in mean values of visual acuities, both uncorrected from 0.71 (preoperatively) to 0.28 (log MAR), and best-corrected from 0.28 to 0.10 (log MAR), mean cylindrical refraction from - 2.35 ± 1.51 to - 4.15 ± 2.23 D, and mean spherical equivalent from - 2.10 ± 2.25 to - 4.64 ± 3.2 D. There was also a reduction in maximal keratometry from 54.21 D preoperatively to 50.93 D postoperatively.

CONCLUSION

The implantation of the progressive thickness ICRS is an effective and safe method to improve the vision of keratoconic eyes. Corneal stability was maintained at the 12-month mark.

Extrusion of Femtosecond Laser-Implanted Intrastromal Corneal Ring Segments in Keratoconic Eyes: Prevalence, Risk Factors, and Clinical Outcomes

Purpose

To evaluate the prevalence, possible risk factors, and clinical results of femtosecond laser implanted intrastromal corneal ring segment (ICRS) extrusion in keratoconic eyes. Patients and Methods. This is a retrospective observational study evaluating 333 eyes of 269 patients who were subjected to femtosecond laser-implanted Keraring ICRS in the Sohag Refractive Center, Sohag, Egypt, from January 2014 to January 2019. The study included eyes with channels created by a femtosecond laser (60 kHz IntraLase femtosecond system; Advanced Medical Optics, Santa Ana, California, USA) with implantation of Keraring intrastromal corneal ring segments (Mediphacos, Belo Horizonte, Brazil). Patient data and causes of Keraring extrusions were identified as being those rings that migrated or showed melting of the cornea with no other reason which required segment removal.

Results

Seven eyes were found to fit the criteria of ring extrusion (2.1%) out of the 333 eyes which had Keraring implantation. All extruded rings were from patients with keratoconus grade 3, with eccentric cones, and with femtosecond creation of the tunnel. Four eyes belonging to 3 patients (57.1%) had a history of vernal Keratoconjunctivitis, yet they did not show signs of activity at the time of implantation. They reported excessive rubbing just before they presented with conjunctival hyperemia and foreign body sensation. Five eyes (71.4%) showed chronic sun exposure. The mean minimal corneal thickness was 401.85 μm (range 384–420 μm), while the mean maximum keratometry was 61 D (range 55.18–68.96 D). Most of the extruded rings had large arcs. Six eyes had crosslinking (CXL) at the same session of the Keraring implantation. The simultaneous CXL treatment is considered as a possible significant risk factor for ring extrusion.

Conclusion

ICRS is an effective reversible option for patients with keratoconus who are intolerant to hard contact lenses, yet the choice of cases and ring segments is mandatory for satisfactory results. Moreover, meticulous history taking and examination reduces the incidence of complications including extrusion.

Intracorneal Ring Segments Implantation Outcomes Using Two Different Manufacturers' Nomograms for Keratoconus Surgery

PURPOSE

To compare the outcomes of intracorneal ring segments (ICRS) implantation in keratoconic eyes with a similar tomographic pattern, using two different manufacturers' nomograms for surgical planning.

METHODS

ICRS were implanted alternately in patients with the same tomographic pattern of keratoconus divided into two groups according to the surgical planning proposed by the ICRS manufacturers (Keraring, Mediphacos, Belo Horizonte, Brazil, and Ferrara Ring, AJL Ophthalmics, Vitoria, Spain). Visual, refractive, keratometric, corneal aberrometry, and optical quality changes were evaluated during a 6-month follow-up. Corneal and manifest refractive astigmatic changes were also analyzed using the double-angle polar plot and the Alpins vectorial method through the following components: target induced astigmatism, surgically induced astigmatism, difference vector, correction index, angle of error, index of success, flattening effect, and torque.

RESULTS

After ICRS implantation, both groups showed significant improvement (P < .05) in visual and keratometric data. Corneal aberrometric changes and optical quality improvement were also statistically significant in both groups, except for trefoil (P > .05 in all intervals). The Alpins method analysis showed a better performance in the Keraring group, but with no statistically significant difference between groups (P > .05). Comparison between groups showed a statistically significant difference only in tomographic astigmatism in double-angle polar plot analysis (P = .03), with more significant improvement in the Keraring group.

CONCLUSIONS

Both manufacturers' nomograms resulted in statistically significant improvement in most of the parameters analyzed, with greater correction of corneal tomographic astigmatism in the group operated on according to the spherical equivalent/tomographic astigmatism nomogram. [J Refract Surg. 2019;35(10):673-683.].

Evaluation of a Tangential Map-Based Nomogram for Intrastromal Corneal Ring Segments' Implantation in Keratoconus: One Year Results

Purpose

To evaluate a new tangential map-based nomogram versus the axial map-based nomogram for ICRS in keratoconus.

Methods

A prospective case series study including 64 eyes of 64 patients who underwent ICRS implantation. Cone location was determined for each eye with two maps: the axial and the tangential. Appropriate ring selection was determined using two surgical nomograms: axial map-based and tangential map-based. Visual, refractive, and topographic outcomes were assessed before, as well as at 3, 6, and 12 months after ICRS implantation.

Results

The cone location, and consequently the ring selection, was significantly different in the two nomograms with a “centralization tendency” in the tangential map. In the axial group, UDVA and CDVA improved from 0.12 ± 0.04 and 0.24 ± 0.08 to 0.28 ± 0.08 and 0.4 ± 0.1, respectively. Similarly, MRSE substantially decreased from −6.7 ± 3.3 to −1.2 ± 1.1D at 12 months after the procedure. In the tangential group, UDVA and CDVA improved from 0.09 ± 0.06 and 0.2 ± 0.1 to 0.5 ± 0.2 and 0.7 ± 0.2, respectively. MRSE substantially decreased from −4.9 ± 1D at 12 months after the procedure. In the tangential group, UDVA and CDVA improved from 0.09 ± 0.06 and 0.2 ± 0.1 to 0.5 ± 0.2 and 0.7 ± 0.2, respectively. MRSE substantially decreased from −4.9 ± 1D at 12 months after the procedure. In the tangential group, UDVA and CDVA improved from 0.09 ± 0.06 and 0.2 ± 0.1 to 0.5 ± 0.2 and 0.7 ± 0.2, respectively. MRSE substantially decreased from −4.9 ± 1P=0.01^∗. Similarly, the gain in the CDVA was 0.4 and 0.15 in the tangential and axial groups, respectively, at 12 months, P=0.01^∗. Similarly, the gain in the CDVA was 0.4 and 0.15 in the tangential and axial groups, respectively, at 12 months,

Conclusion

The tangential map-based nomogram attained better visual and refractive outcomes at 1 year. In addition, the cone location was significantly different between both maps with a centralization tendency in the tangential one.

Novel technique of fixing intracorneal rings segments after migration

A 38-year-old patient with a history of non-progressive keratoconus in the left eye presented to us with an uncorrected visual acuity of 20/400, which improved to 20/60 with pinhole. We planned for intracorneal rings segment in the left eye. Postoperatively uncorrected visual acuity improved to 20/30. The patient presented 2 weeks later with severely decreased vision to 20/100 and migration of intracorneal rings were noted with both the rings riding side by side. The patient gave history of vigorous eye rubbing. The rings were repositioned with the help of Sinskey hooks and superior ring was anchored with 10-nylon suture passed through the ring hole to the corneal stroma. Two more sutures were placed radial to the circumference of inferior ring to prevent its migration. The sutures were removed after 1 month and the patient was followed up with stable position of the rings for the next 6 months . The uncorrected visual acuity improved to 20/40.

Corneal collagen cross-linking with and without simultaneous intrastromal corneal ring segment implantation: One-year pilot study

AIM

The aim of this study was to assess and compare the visual, refractive, and topographic outcomes of keratoconic eyes treated with corneal collagen cross-linking combined with and without same day intrastromal corneal ring segment over the first 12 months.

METHODS

This prospective randomized study analyzed 38 eyes of 30 consecutive keratoconus patients aged 26.21 ± 6.97 (range = 15-41) years. A total of 20 eyes were treated with collagen cross-linking alone, and 18 eyes underwent collagen cross-linking combined with simultaneous femtosecond laser-assisted intrastromal corneal ring segment. Visual acuity, manifest refraction, and corneal topography (using a rotating Scheimpflug topographer) were assessed and compared between the two groups at baseline, 6, and 12 months.

RESULTS

On an average follow-up duration of 12.2 ± 0.50 (range = 11-13) months, both collagen cross-linking alone and collagen cross-linking with simultaneous intrastromal corneal ring segment implantation were effective. However, collagen cross-linking plus intrastromal corneal ring segment resulted in an additional improvement of uncorrected distance visual acuity of 0.16 (95% confidence interval = 0.01 to 0.32) logarithm of the minimum angle of resolution units (p = 0.035), cylindrical power by 1.16 D (95% confidence interval = 0.25 to 2.06, p = 0.014), and spherical equivalent by 1.40 D (95% confidence interval = -2.71 to -0.08, p = 0.038) at 1 year. During the study period, no serious intraoperative or postoperative complications were noted in either group.

CONCLUSION

One-year follow-up results suggest that collagen cross-linking with simultaneously combined intrastromal corneal ring segment implantation could yield an additive visual and refractive outcome. The combined procedure is safe and merits consideration for the treatment of progressive keratoconus to achieve better visual rehabilitation.

Intracorneal Ring Segment Implantation in the Management of Keratoconus: An Evidence-Based Approach

Intracorneal ring segment (ICRS) implantation represents a modern, minimally invasive, surgical option for visual improvement in patients with keratoconus. ICRS modify the corneal geometry in a manner that enhances its refractive properties and thereby, they improve visual acuity. It is well-documented that implantation of ICRS decreases the keratometric readings, spherical equivalent and cylinder, reduces high-order aberrations and improves uncorrected distance visual acuity (UDVA) and best-corrected distance visual acuity (BCDVA) in patients with keratoconus. Success rate after ICRS implantation is high, depending on appropriate patient selection and adherence to suitable implantation nomograms, and most important, the overall complication rate is very low. This review is summarizing current indications/contra-indications for ICRS implantation, implantation techniques, clinical outcomes and potential complications, shedding light on myths and realities related to this innovative surgical option.

Three-year follow-up of intrastromal corneal ring segment implantation in central keratoconus with regular astigmatism: ‘Bow-tie’ shape

Purpose:

To assess the outcomes of implanting Ferrara-type intrastromal corneal ring segments in central ‘bow-tie’-shaped keratoconus over 3 years of follow-up.

Methods:

A total of 20 eyes with central ‘bow-tie’-shaped keratoconus were evaluated before and after implanting Ferrara-type intrastromal corneal ring segments (AJL Ophthalmic, Spain). LogMAR uncorrected distance visual acuity and best corrected distance visual acuity and residual refractive errors analysed using vector analysis were recorded preoperatively, at 6 months, 1 year, and 3 years postoperatively.

Results:

The mean uncorrected distance visual acuity (LogMAR scale) rose from a preoperative 0.75 ± 0.28 to a 6-month postoperative 0.38 ± 0.28 (p < 0.0001). The corrected distance visual acuity, in turn, improved from 0.07 ± 0.06 to 0.05 ± 0.06 (p = 0.0008). Both the uncorrected distance visual acuity and corrected distance visual acuity were stable over the postoperative period in both groups (p > 0.05). None of the eyes lost uncorrected distance visual acuity and corrected distance visual acuity lines over the postoperative follow-up period. The spherical equivalent and the refractive cylinder declined steeply after intrastromal corneal ring segments implantation (p < 0.0001). Both the spherical equivalent and refractive cylinder were stable over the postoperative period. None of the eyes had an increase in maximum or minimum keratometry greater than 0.75D over the postoperative period.

Conclusion:

The planning for intrastromal corneal ring segments insertion proposed in this study reduces the spherical equivalent and refractive cylinder in this type of keratoconus, while improving post-surgery uncorrected distance visual acuity and corrected distance visual acuity. These results remain stable over 3 years of follow-up. Therefore, this procedure could be considered as an effective therapeutic alternative in patients affected by this type of keratoconus.

Long-term outcome of intrastromal corneal ring segments in keratoconus: Five-year follow up

To evaluate the effectiveness of intrastromal corneal ring segment (ICRS) use in keratoconus after five years. ICRS has been widely used to correct astigmatism and improve visual acuity in keratoconus. Although the short-term outcome is well known to be effective, long-term outcome has rarely been reported. A retrospective chart review was done. A total of 30 eyes diagnosed with keratoconus and treated with INTACS (Addition Technology, Sunnyvale, CA, USA) were included. Visual acuity, refraction, indices of corneal irregularity, and higher-order aberration were evaluated at preoperative, two months, one year, three years, and five years postoperatively. Uncorrected distance visual acuity (UDVA) and spherical and spherical equivalent were improved (p < 0.05) for three years. However, they worsened (p < 0.05) at five years to preoperative values. On the other hand, corrected distance visual acuity (CDVA) was improved for five years (p < 0.05). Topographic keratometry was flattened, and corneal irregularity indices were improved at five years (all p < 0.05). Coma RMS was improved (p < 0.05) continuously for five years. ICRS has advantages in improving CDVA with topographic stabilization and decreasing coma in keratoconus for five years.

Pediatric keratoconus: a review of the literature

PURPOSE

To describe the epidemiology and prevalence, rates of progression, difference between adult and pediatric populations, and therapeutic approaches to pediatric keratoconus from documented literature.

METHODS

A literature search was done on PubMed using key words including pediatric keratoconus, children with keratoconus, adult keratoconus, penetrating keratoplasty, corneal cross-linking and intracorneal ring segments. The literature was reviewed and reported to explore the key epidemiological differences between the pediatric and adult population with regards to presentation and treatment options.

RESULTS

Pediatric keratoconus is more aggressive than adult keratoconus, which has been explained by structural differences in the cornea between both populations. High rates of progression were documented in pediatric populations. While corneal collagen cross-linking, intracorneal ring segments and penetrating keratoplasties have been used as therapies in the pediatric population, the literature overwhelmingly shows higher rates of failure and progression despite these measures as compared to adults.

CONCLUSION

Pediatric keratoconus is more aggressive than adult keratoconus, and current therapies used in adults may not be sufficient for the pediatric population.

Corneal imaging and densitometry measurements in keratoconus patients to monitor disease progression and treatment outcomes after contact lens or Intacs treatment

Aim

The aim of this study was to compare the pre- and posttreatment corneal densitometry and corneal thickness value of keratoconus (KCN) patients managed via contact lenses (CLs) or by both intrastromal corneal rings and contact lenses.

Patients and methods

This prospective study was performed at the Manchester Royal Eye Hospital, UK. Patients were recruited before treatment and followed up for 12 months. Data of corneal densitometry and corneal thickness were collected using the Oculus Pentacam at the pretreatment visit and posttreatment visit at 12 months.

Results

Corneal clarity significantly differs between both groups at pre treatment at zone 0-2 mm for the anterior layer (P=0.002). The same diversity is present at zone 2-6 mm for the anterior layer (P=0.003) and posterior layer (P=0.008). The corneal clarity diversity found was not statistically significant at 12 months post treatment (P>0.05). Corneal thickness was found to be statistically significantly different between pre treatment and post treatment for the CL group for central corneal thickness (CCT) and thinnest area (P=0.01 and P=0.02), respectively.

Discussion

This study shows that KCN management with Intacs was found to be effective in maintaining corneal clarity for a longer time than that with CL alone. On the other hand, corneal clarity reduces with disease progression in cases managed with CLs only. Analysis of Oculus Pentacam images provides an objective evaluation to monitor the corneal status after these different pathways of management.

A Review of Corneal Collagen Cross-linking - Current Trends in Practice Applications

Objective:

To review the literature on current applications of corneal Collagen Cross-Linking (CXL).

Methods:

A review of publications on corneal cross-linking was conducted. This included systemic reviews, randomized controlled clinical trials, cohort studies, case-controlled studies and case series. A summary of the publications is tabulated.

Results:

The original indication of riboflavin – Ultraviolet-A (UVA) induced corneal collagen cross-linking is to arrest the progression of keratoconus. Studies show that it is effective in arresting the progression of keratoconus and post-LASIK ectasia with the standard Dresden protocol (epithelium-off). There are also improvements in visual, keratometric and topographic measurements over time. Severe complications of cross-linking are rare. The epithelium-on techniques have less efficacy than the Dresden protocol. Accelerated protocols have variable results, with some studies reporting comparable outcomes to the Dresden protocol while other studies reporting less efficacious outcomes. Cross-linking combined with refractive procedures provide better visual outcome but long term studies are warranted. Cross-linking for the treatment of infective keratitis is a promising new treatment modality. Initial studies show that it is more effective for superficial rather than deep infections and for bacterial rather than fungal infections.

Conclusions:

Corneal cross-linking is a procedure with an expanding list of indications from the treatment of corneal ectasias to infective keratitis. While the standard Dresden protocol is established as the gold standard treatment for progressive keratoconus, the more recent protocols may require further refinements, investigative and long-term studies.

Changes in the ABCD Keratoconus Grade After Intracorneal Ring Segment Implantation

PURPOSE

To assess the changes in the ABCD keratoconus staging system 6 months after intracorneal ring segment implantation.

METHODS

Fifty eyes of 50 patients with keratoconus who were implanted with the Keraring (Mediphacos, Belo Horizonte, Brazil) using the femtosecond laser were assessed. Preoperative and postoperative assessments included determination of distance uncorrected visual acuity and distance corrected visual acuity (DCVA), refraction, and Scheimpflug tomography with the Pentacam HR. In the ABCD keratoconus staging system, the elements A, B, C, and D stand for anterior and posterior radii of curvature in a 3.0-mm zone centered on the thinnest point (TP), corneal thickness at the TP, and DCVA, respectively.

RESULTS

Keraring implantation produced significant flattening changes (preoperatively vs. postoperatively) in the anterior (6.60 ± 0.48 vs. 7.22 ± 0.57 mm, P < 0.001) and posterior (4.99 ± 0.47 vs. 5.16 ± 0.53 mm, P = 0.002) radii of curvature of the 3-mm zone centered on the corneal TP associated with a statistically significant improvement in the DCVA (0.56 ± 0.24 vs. 0.70 ± 0.22 in the decimal notation, P = 0.001) with no significant change in the corneal thickness at the TP (P = 0.285). The most changes occurred in element A of the ABCD keratoconus classification. Also, a 1-stage change was observed for element B, whereas elements C and D did not show changes in their postoperative stages after ring implantation. ABCD keratoconus staging before ring implantation was A2B3C2D1 and changed to A1B2C2D1 6 months after surgery.

CONCLUSIONS

The ABCD staging system provides a more comprehensive guide that better illustrates the structural changes and visual acuity as one aspect of visual function after the implantation of the intrastromal corneal ring segments.

Implantation of intracorneal ring segments in pediatric patients: long-term follow-up

Purpose

To analyze the long-term outcomes of intracorneal ring segments (ICRS) implantation for keratoconus management in pediatric patients.

Methods

Retrospective case series review of the long-term (>5 years) outcomes of Intacs^® ICRS implantation for keratoconus in pediatric patients (age <18 years old at the time of surgery) between January 2008 and December 2011 at Ophthalmology Department of Hospital de Santo António. Demographic data, follow-up time, preoperative and postoperative uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA) in decimal scale, and corneal topography were evaluated. Statistical analysis was done using SPSS for windows (version 24). Significance was set at p<0.0125.

Results

Fourteen eyes of 14 patients, with a mean age of 15.36 years (range 10-18 years), were included in this study. All patients had been diagnosed with keratoconus with reported progression in the 6 months prior to surgery. Follow-up time was 6.36±0.97 years. UCVA and BCVA improved after ICRS implantation (p<0.0125). Keratometry (K) minimum (Kmin) and K maximum (Kmax) decreased after surgery (p<0.0125). During follow-up, UCVA, BCVA, Kmin, and Kmax values ranged, showing a tendency to worsen at the end of follow-up. However, statistically significant differences were not observed.

Conclusion

ICRS implantation showed good visual and topographic results in pediatric patients. Long-term follow-up suggests that, despite ICRS implantation, there is still progression of keratoconus. To the best of our knowledge, there are no reports regarding the long-term efficacy of ICRS implantation in pediatric patients.

Late Onset of Deep Corneal Vascularization: A Rare Complication of Intrastromal Corneal Ring Segments for Keratoconus

Purpose

To report deep corneal vascularization noted 3 years after intrastromal corneal ring segments (Intacs) implantation for the treatment of keratoconus.

Methods

A 33-year-old male keratoconus patient intolerant to rigid gas permeable contact lens in the right eye underwent Intacs implantation. At 2 years postoperatively, slit-lamp examination of the right eye revealed superficial corneal vascularization inferotemporally, extending 1.5 mm from the limbus. At 3 years postoperatively, the slit-lamp examination of the right eye revealed deep stromal vascularization extending to and arborizing along the temporal segment. Also, superficial vascularization was noted along the nasal segment inferiorly. The Intacs segments were then explanted.

Results

On post-explantation day 10, the deep vessels regressed to ghost vessels with topical corticosteroid therapy.

Conclusions

The authors present a rare case where deep corneal vascularization was noticed 3 years following Intacs implantation for keratoconus. All patients having superficial vascularization away from the incision site need to be followed for this rare complication.

Long-term outcomes of corneal cross-linking for keratoconus in pediatric patients

PURPOSE

To report the long-term outcomes of corneal cross-linking (CXL) in pediatric patients with bilateral progressive keratoconus.

METHODS

The medical records of consecutive pediatric patients with bilateral progressive keratoconus who underwent CXL at a single institution from June 2007to December 2009 were reviewed. All eyes underwent CXL treatment in accordance with the original Dresden protocol. Pre- and post-operative (at 1 year and >5 years after CXL) examinations included, corneal thickness (CT) at the thinnest point, corneal topographic evaluation (flat, steep meridian keratometry and maximum keratometry), with manifest refraction and corrected distance visual acuity.

RESULTS

A total of 20 eyes of 10 patients were included. Mean age at time of CXL was 14.34 ± 2.14 years (range, 10.49-17.09 years). Mean follow-up was 7.63 ± 1.31 years (range, 5.41-9.34 years). No intra- or postoperative complications were observed. Stabilization of all topographic indices (steep K, flat K, Kmax, and topographic cylinder) was demonstrated throughout the follow-up period (compared to preoperative topographic indices [P < 0.05]). Mean corrected distance visual acuity improved to 0.14 ± 0.16 logMAR at final follow-up from the preoperative values 0.28 ± 0.17 logMAR (P > 0.05); none of the eyes lost corrected distance visual acuity lines. Manifest refraction and mean corneal pachymetry at the thinnest point remained stable throughout the follow-up (P < 0.05).

CONCLUSIONS

In this case series CXL (Dresden protocol) for pediatric keratoconus halted disease progression and offered improved visual function up to 7.5 years after treatment.

Long-Term Follow-Up of Intrastromal Corneal Ring Segments in Paracentral Keratoconus with Coincident Corneal Keratometric, Comatic, and Refractive Axes: Stability of the Procedure

Purpose

To assess the long-term outcomes of implanting intrastromal corneal ring segments (ICRS) in paracentral keratoconic eyes.

Methods

58 eyes with paracentral keratoconus with coincident refractive, keratometric, and comatic axes were evaluated. Uncorrected (UDVA) and corrected (CDVA) distance visual acuity and refractive errors were recorded before and at all follow-up visits. The postoperative follow-up was 5 years. Patients were divided into two groups: group I (30 years old or younger) and group II (more than 30 years old).

Results

The mean UDVA (logMAR) rose from a preoperative 0.83 ± 0.31 to a five-year postoperative 0.42 ± 0.33 (P < 0.0001). The mean CDVA varied from 0.16 ± 0.17 to 0.11 ± 0.18 (P = 0.0003). Both the UDVA and CDVA were stable over the postoperative period in both groups (P > 0.05). The spherical equivalent and the refractive cylinder declined steeply after ICRS implantation in both groups (P < 0.001), and were stable over the postoperative period (P > 0.05). The keratometric values were also stable over the postoperative follow-up.

Conclusion

Ferrara-type ICRS implantation in keratoconus that meets the characteristics of the sample under study reduces the refractive error at the same time as it improves postoperative UDVA and CDVA six months after surgery and that these results remain stable over five years of follow-up.

Updates on corneal collagen cross-linking: Indications, techniques and clinical outcomes

Purpose

To review the historical background and basic principles of collagen cross-linking, to bring together the data regarding the outcomes and complications of collagen cross-linking and finally to explore the efficacy and safety of new variations of this technique.

Methods

A literature review was performed using PubMed and Scopus. The following keywords were used for literature search: cross linking, crosslinking, cross-linking, keratoconus, keratectasia.

Results

In contrast to traditional treatment modalities for keratoconus (KCN), this new technique addresses the progression of the disease. Several clinical studies have been conducted to assess the efficacy of corneal collagen cross-linking (CXL) in the last decade. The results were promising as collagen cross-linking showed significant improvement in visual acuity and keratometric values. Moreover, initial results show that it is a safe procedure with few reported complications.

Conclusion

CXL is an emerging treatment method in ophthalmology that offers the possibility to effectively treat progressive KCN.

Keraring implantation using the Zeiss Visumax femtosecond laser in the management of patients with keratoconus

PurposeTo evaluate the safety and efficacy of implanted Kerarings in patients with mild, moderate, and severe keratoconus.Patients and methodsA 12-month retrospective case series of 70 eyes of 70 patients who underwent Keraring implantation with the Zeiss Visumax femtosecond laser. Patients were stratified into three groups according to their topography as mild (mean K <48 D) moderate (48-55 D) or severe (>55 D). Main outcome measures were visual acuity, manifest refraction, and corneal topography. Complications were recorded.ResultsA total of 66 patients completed the 12-month follow-up. In all, 4 rings were explanted, 3 due to no improvement in visual function and 1 due to corneal neovascularization. Also, 4 rings were repositioned. In mild disease (n=28), BCVA increased to 0.10 logMAR, sphere decreased to -1.54 D, cylinder decreased to 2.54 D, Kmax decreased to 46.25 D, and keratometric astigmatism to 3.88 D (P<0.01 for each compared with preoperative values). No patients lost vision. In moderate disease (n=27), sphere decreased to -4.06 D, cylinder decreased to 3.47 D, Kmax decreased to 51.69 D, and keratometric astigmatism to 4.56 D (P<0.05 for each compared with preoperative values). In severe disease (n=11), BCVA increased to 0.34 logMAR, Kmax decreased to 57.65 D, and keratometric astigmatism to 5.07 D (P<0.05 for each compared with preoperative values).ConclusionFemtosecond laser-assisted Keraring implantation is a safe and minimally invasive treatment option to improve the refraction and visual function in patients with keratoconus. Patients with mild keratoconus are more likely to have a favourable outcome following Keraring implantation.

Effects of single-segment Intacs implantation on visual acuity and corneal topographic indices of keratoconus

PURPOSE

To assess the changes in visual acuity and topographic indices after implantation of single-segment Intacs.

METHODS

Forty-two keratoconic eyes received Femtosecond-assisted single-segment Intacs. Uncorrected distance visual acuity (UDVA) and best spectacle corrected visual acuity (BSCVA), refractive error, keratometry (K1, K2, Km, and KMax.), and seven Pentacam measured topographical indices; index of surface variance (ISV), index of vertical asymmetry (IVA), keratoconus index (KI), central keratoconus index (CKI), index of height asymmetry (IHA), index of height decentration (IHD), and minimum radius of curvature (R Min) were assessed 4 months after surgery. Correlations between changes of visual acuity and topographical indices changes were evaluated.

RESULTS

UDVA increased from 0.92 ± 0.35 to 0.49 ± 0.31 logMAR (P < 0.001), and BSCVA increased from 0.39 ± 0.15 to 0.23 ± 0.11 logMAR (P < 0.001). Subjective refraction spherical equivalent (SRSE) decreased from -3.92 ± 1.66 diopters (D) to -2.00 ± 1.51 D (P < 0.001). Mean central Keratometry decreased 2.16 ± 1.09 D from the preoperative readings (P < 0.001). All Pentacam topographical indices except CKI significantly improved (for IHA P = 0.046, for five others P < 0.001). The correlation between improvement in topographical indices and visual acuity improvements was not week.

CONCLUSION

Intacs implantation in keratoconic eyes increased visual acuity and made corneal shape less irregular. However, the improvements of visual acuity and corneal shape were not strongly correlated.

Efficacy of Intrastromal Corneal Ring Segments Combined With Flash Collagen Cross-Linking in Keratoconus

PURPOSE

To evaluate outcomes, efficacy, and safety of intrastromal corneal ring segment implantation for treatment of keratoconus combined with collagen cross-linking (CXL) with 1-year follow-up.

METHODS

One hundred nineteen eyes of 82 patients with keratoconus (37 females) underwent femtosecond (Intralase FS; Abbott Medical Optics, Inc) laser-assisted intrastromal corneal ring segment implantation (INTRASEG; Gamma Vision) with flash CXL (18 mW/cm for 5 minutes). The outcome measures were uncorrected distance visual acuity (UDVA), best-corrected distance visual acuity (CDVA), subjective refractive error, keratometry values, and corneal thickness.

RESULTS

Mean age of patients at implantation was 31 years (range 12-63, SD 9.5). According to the Amsler-Krumeich scale of keratoconus severity, 62 eyes were type 1 (52%), 43 eyes, type 2 (36%), and 14 eyes, type 3 (11.8%). Statistically significant improvement of UDVA/CDVA and reduction in the mean cylinder and mean keratometry at 1 year were observed. Mean UDVA (logMAR) was 1.11 ± 0.61 (SD) preoperatively and 0.54 ± 0.58 (SD) postoperatively (P < 0.001). Mean CDVA was 0.52 ± 0.18 (SD) preoperatively and was 0.14 ± 0.17 (P < 0.0001) postoperatively. Preoperative Kmax was 48.75 diopters (D) (range 41.0-55.0 D), and postoperative Kmax was 46.18 D (P < 0.0006); preoperative Kmin was 44.69 D (SD) 3.59 and postoperative Kmin was 43.00 D (SD) 2.53. The mean cylinder was -5.19 D preoperatively (range -0.80 to -8.80 D) and -2.6 D (range -1.00 to -7.25) postoperatively. Mean corneal pachymetry was 486.6 μm (range 391-591). No intraoperative complications occurred. No patient lost any lines of UDVA or CDVA.

CONCLUSIONS

Implantation of the INTRASEG with the Intralase combined with flash CXL was apparently safe and effective in treatment of keratoconus. The variety of options in thickness and arc length of the segments enables more precise correction of keratoconus and refractive errors.

Intrastromal Corneal Ring Segments in Children with Keratoconus

Purpose

To evaluate the long-term follow-up of Ferrara intrastromal corneal ring segments (ICRSs) (Ferrara Ophthalmics, Belo Horizonte, Brazil) implantation for the management of keratoconus in children.

Study design

Paulo Ferrara Eye Clinic, Belo Horizonte, Minas Gerais, Brazil.

Materials and methods

A total of 58 eyes of 37 children with keratoconus were included. One or two ring segments were inserted into the cornea, embracing the keratoconus area. Statistical analysis included preoperative and postoperative uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), asphericity, pachymetry, and keratometry.

Results

Ferrara ICRS implantation significantly improved the mean UDVA and CDVA. Corneal tomography (Pentacam®) showed corneal flattening in all eyes implanted with the Ferrara ring. The mean K decreased, and the corneal asphericity and pachymetry increased in all cases.

Conclusion

The Ferrara ICRS improved all parameters after 2 years of implantation in children with keratoconus. There was significant corneal flattening after ring implantation with improvement of the UDVA and the CDVA. All studied parameters remained stable over time.

How to cite this article

Ferrara G, Ferrara P, Torquetti L. Intrastromal Corneal Ring Segments in Children with Keratoconus. Int J Kerat Ect Cor Dis 2017;6(2):45-48.

Confocal biomicroscopic changes of the corneal layers following femtosecond laser-assisted MyoRing implantation in keratoconus

Purpose

To evaluate the effect of the femtosecond laser-assisted MyoRing implantation on the confocal biomicroscopic findings in different corneal layers of the patients with keratoconus.

Methods

Twelve eyes of 12 patients with mild to moderate keratoconus (keratometry between 48 and 52 diopters) and intolerance to hard contact lens entered the study. All the included patients underwent femtosecond laser-assisted MyoRing (Dioptex GmBH, Linz, Austria) implantation. The confocal biomicroscopy of the cornea was performed for all corneal layers in the center and periphery preoperatively and 3 and 6 months postoperatively. The cell counts and the qualitative findings in each layer of the cornea were compared between preoperative and 3 and 6 months postoperative images.

Results

Compared with preoperative values, the central epithelial and the central and peripheral midstromal cell counts were significantly decreased 6 months after MyoRing implantation (P = 0.015, P = 0.010 and 0.005, respectively). Furthermore, compared with preoperative values, the peripheral posterior stromal cell count was significantly decreased 3 months after MyoRing implantation (P = 0.033). In the qualitative analysis, highly reflective nuclei in the basal epithelium, transient disruption in the subepithelial nerve plexus, increase in the reflectivity of the stromal keratocyte, and normal endothelial cell morphology were seen.

Conclusions

Our study demonstrated some findings similar to that reported in intrastromal corneal ring segments (ICRS): decreased central epithelial cell counts, highly reflective nuclei in the basal epithelium, transient disruption in the subepithelial nerve plexus, and normal endothelial cell count and morphology. In addition, a decrease in the central and peripheral midstromal, transient decrease in posterior stromal cell counts, and absence of amorphous depositions were in contrast with the findings reported in ICRS.